A Beginner's Guide to Getting Started with Deno

In the ever-evolving world of JavaScript and server-side development, Deno has emerged as a modern runtime that promises to address some of the shortcomings of its predecessor, Node.js. Created by Ryan Dahl, the original creator of Node.js, Deno is designed to be secure, efficient, and developer-friendly. If you're new to Deno and wondering how to get started, this beginner's guide will walk you through the basics and help you take your first steps with this exciting runtime.

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What is Deno?

Deno is a modern JavaScript and TypeScript runtime built on V8, the same engine that powers Google Chrome. Unlike Node.js, Deno is designed with security and simplicity in mind. It comes with several key features that make it stand out:

• Built-in TypeScript support: No need for additional tools or configurations to run TypeScript code.
• Secure by default: Deno restricts file system, network, and environment access unless explicitly allowed.
• Single executable: Deno is distributed as a single binary, making installation and updates straightforward.
• Standard library: Deno includes a curated standard library for common tasks, reducing the need for third-party dependencies.
• Modern module system: Deno uses ES modules and URLs for importing dependencies, eliminating the need for a package.json file or a centralized package registry like npm.

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Why Choose Deno?

If you're already familiar with Node.js, you might wonder why you should consider learning Deno. Here are a few reasons:

1. Security: Deno's permission-based execution model ensures that your code cannot access sensitive resources without explicit permission.
2. TypeScript Support: With built-in TypeScript support, you can write modern, type-safe code without additional setup.
3. Simplified Dependency Management: Deno uses URLs to import modules, making it easier to manage dependencies without relying on a package manager.
4. Improved Developer Experience: Deno's standard library and built-in tools (like a linter, formatter, and test runner) streamline the development process.

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Installing Deno

Getting started with Deno is quick and easy. Follow these steps to install it on your system:

1. Install Deno

Deno provides a simple installation process for all major operating systems. Open your terminal and run the following command:

# Using Shell (Linux and macOS)
curl -fsSL https://deno.land/install.sh | sh

# Using PowerShell (Windows)
iwr https://deno.land/install.ps1 -useb | iex

Alternatively, you can use a package manager like Homebrew (macOS) or Chocolatey (Windows):

# macOS (Homebrew)
brew install deno

# Windows (Chocolatey)
choco install deno

2. Verify Installation

Once installed, verify that Deno is working by running:

deno --version

You should see the installed version of Deno along with its V8 and TypeScript versions.

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Writing Your First Deno Script

Now that Deno is installed, let’s write a simple script to get a feel for how it works.

1. Create a New File

Create a new file called hello_deno.ts and add the following code:

console.log("Hello, Deno!");

2. Run the Script

Run the script using the deno run command:

deno run hello_deno.ts

You should see the output:

Hello, Deno!

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Exploring Deno's Key Features

Deno comes with several built-in features that make it a powerful runtime. Let’s explore a few of them:

1. Permissions

By default, Deno restricts access to the file system, network, and environment variables. To grant permissions, you need to use specific flags. For example:

deno run --allow-read read_file.ts

This ensures that your scripts only have access to the resources they need, improving security.

2. Importing Modules

Deno uses ES modules and URLs for importing dependencies. For example:

import { serve } from "https://deno.land/[email protected]/http/server.ts";

serve(() => new Response("Hello, Deno!"));

No need for a package.json file or node_modules directory—just import what you need directly from the web.

3. Built-in Tools

Deno includes several built-in tools to enhance your development workflow:

• Formatter: Automatically format your code with deno fmt.
• Linter: Analyze your code for potential issues with deno lint.
• Test Runner: Write and run tests with deno test.

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Building a Simple HTTP Server with Deno

To see Deno in action, let’s build a simple HTTP server. Create a new file called server.ts and add the following code:

import { serve } from "https://deno.land/[email protected]/http/server.ts";

const port = 8000;
console.log(`HTTP server is running on http://localhost:${port}/`);

serve((req) => new Response("Hello, Deno!"), { port });

Run the server with the following command:

deno run --allow-net server.ts

Open your browser and navigate to http://localhost:8000/. You should see the message "Hello, Deno!" displayed in your browser.

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Next Steps

Congratulations! You’ve taken your first steps with Deno. Here are some suggestions for what to explore next:

1. Deno Documentation: Visit the official Deno documentation to learn more about its features and APIs.
2. Standard Library: Explore the Deno standard library for utilities like file handling, HTTP servers, and more.
3. Third-Party Modules: Check out deno.land/x for a collection of third-party modules.
4. Build a Project: Start a small project, such as a REST API or a CLI tool, to deepen your understanding of Deno.

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Final Thoughts

Deno is a powerful and modern runtime that offers a fresh take on server-side JavaScript and TypeScript development. With its focus on security, simplicity, and developer experience, it’s an excellent choice for building scalable and maintainable applications. Whether you’re a seasoned developer or just starting out, Deno is worth exploring.

So, what are you waiting for? Install Deno, write your first script, and start building amazing things today!